The present invention relates to an interlock system for use with multiple vertically arranged drawers or storage units mounted via telescoping slide assemblies in a unit such as a lateral drawer file cabinet. The interlock system prevents the opening of a second drawer when one drawer is open so as to prevent the tipping over of the file cabinet.
Cabinets with multiple vertically arranged drawers may tilt over when more than one drawer is open at the same time, creating a hazard. The tilting of the cabinet is caused by the shifting of the cabinet center of gravity when two or more drawers are opened. Tilting of a cabinet is especially likely to occur when the open drawers contain relatively heavy materials.
To prevent such tilting, many cabinets with vertically arranged drawers incorporate interlock systems which prevent a drawer from being opened if another drawer is open. Some interlock systems in use today interface with the rear portion of the file drawers as is illustrated in U.S. Pat. No. 4,480,883. Their location makes their installation and repair difficult. Moreover, the position of such interlock systems make it difficult to interface these systems with locking systems which are typically located at the front of the cabinet on either side of the top portion of the file housing.
Current interlock systems require that their components be installed or removed in a sequential order. For example, interlock components positioned between the lowermost slides must be installed prior to components located between the uppermost slides. An example of this design is an interlock system utilizing a stack of latch bars which is disclosed in U.S. Pat. No. 4,637,667. Furthermore, components located proximate to the lowermost slides cannot be removed without first removing the components located proximate to the uppermost slides. This makes for a complex, time consuming, and costly interlock system installation and removal process.
In addition, most interlock system in use today are designed for use with drawers of a specific predetermined height and cannot be easily altered for use with drawers of different heights.
Most interlock systems in use today also require that their components be built to precise tolerances. A shift in these tolerances may result in interlock system malfunction.
Rotational cam interlock systems, also currently used, such as disclosed in PCT Application Serial No. PCT/CA93/00359 (International Publication No. WO94/07989) rely on instantaneous actuation upon drawer openings and may not always maintain a constant displacement while the drawer is open. Consequently, they do not provide for a positive and maintained actuation so as to prevent system malfunction. This could result in inadvertent unlocking of the drawers.
Accordingly, there is a need for an interlock system which can interface with the front of the slides used to couple the drawers to a cabinet or other housing and which can interface with the cabinet locking system. Moreover, an interlock system is needed that is easy to install, that does not require precise tolerances, and that can be easily altered for use with drawer arrangements comprising drawers of different heights.
The present invention provides a drawer slide interlock system for use with two or more vertically arranged drawers mounted on left and right sets of vertically spaced apart telescoping slides in a housing such as a file cabinet or storage unit. The interlock system may interface with either the left or right set of slides.
Each slide assembly comprises a stationary member which attaches to the cabinet and a telescoping member which attaches to the drawer.
A pair of opposing upper and lower actuator followers are slidably and perpendicularly located adjacent the front end of each stationary member. Each actuator follower may slide from a position blocking the extension path of the telescopic member to a position of not blocking such extension path. Within a slide, as one actuator follower moves toward the other, it abuts the other and displaces it. For example, as the lower actuator follower moves upward, it abuts against the upper actuator follower and displaces it.
Rods are used to interconnect the upper actuator follower of one slide to the lower actuator follower of a higher slide. The rods can easily snap in and, if necessary, snap out of the actuator followers. When connected into the actuator followers, the rods are free to move vertically within reasonable limits.
In one embodiment, an actuator is fitted on the front end of the telescopic member. The actuator has tapered surfaces. Tapered surfaces on the actuator followers come in contact with the actuator tapered surfaces as the telescoping member is extended from its closed position or when it is retracted from an open position. The actuator and actuator followers are preferably made from a polymeric material so as to reduce friction, soften the impact between them and quiet the operation of the slide.
Upon extension of a telescoping member of one slide, the actuator in front of the telescoping member makes contact with the upper actuator follower of that slide and displaces it upwards. The actuator follower is maintained upwardly displaced by the extension of the slide""s intermediate member which is sequenced to initially extend with the slide telescopic member. Consequently, the actuator follower displaces the rod and the interconnected lower actuator on the immediately higher slide, bringing the lower actuator follower of that slide in position to block the extension of the telescoping member of the slide.
Simultaneously, this lower actuator follower displaces its opposing upper actuator follower. This process is simultaneously repeated and as a result, all lower actuator followers on the slides located above the extended slide move into position to block the extension of their respective telescopic members.
Similarly, the extended slide blocks the upward movement of the upper actuator followers of the lower slides. Consequently, all the upper actuator followers of the slides below the extended slide are precluded from moving upwards, thus, remaining in a position blocking the extension of their respective telescopic members.
In an alternate embodiment, the actuator comprises a body and a pair of fingers extending beyond the actuator body. These fingers are flexible or are pivotally coupled to the actuator body. This alternate embodiment actuator is coupled to the front end of the intermediate member of a slide such that the fingers of the actuator extend beyond the slide""s telescopic member when the slide is retracted. When the slide is retracted, the upper finger is in position to engage the upper actuator follower of the slide while the lower finger of the actuator is in position to engage the lower actuator follower of the slide. With this embodiment, extension of the slide telescopic member causes extension of the slide""s intermediate member which is sequenced to extend with the slide""s telescopic member causing the fingers and subsequently the intermediate member to engage and displace upward the slide""s upper actuator follower. With this embodiment actuator, the interlock system still functions as described above. However, if the sequencing mechanism of the slide being extended fails such that the slide""s telescopic member extends without extending the slide""s intermediate member, the slide""s telescopic member will still bias the slide""s actuator upper finger upward causing it to engage and displace the slide""s upper actuator follower upward. Simultaneously, the telescopic member will block the actuator lower finger and thus the lower actuator follower from displacing upward. Consequently, extension of the slides above and below the extended slide is prevented.
A locking mechanism for locking all the slides in a closed position can easily be incorporated into the interlock system of the present invention. For example, a locking mechanism can be positioned such that it interferes with the upward movement of the uppermost actuator follower of the uppermost slide. This will preclude the upward displacement of any upper actuator follower of any slide. Consequently all of the upper actuator followers will be in a position blocking the extension of their respective telescopic members.
Similarly, a locking mechanism can also be incorporated anywhere along the height of the system. For example, a member can be used to bias any of the rods such that all the lower actuator followers on the slides directly above the biasing member are displaced upward, while all the upper actuator followers of the slides directly below the biasing member are prevented from being displaced upward. Consequently, an actuator follower on a slide of each drawer will be in a position to block the extension of its respective telescopic member.